Interleaving apparatus and deinterleaving apparatus

ABSTRACT

A signal record reproduction device  1  of the invention comprises a microcomputer  12  and a memory  17.  A series of data blocks are divided into a plurality of items of element data. The element data is interleaved and stored to the memory  17.  A memory incorporated in the microcomputer  12  stores a table and a function expression for deriving address data representing an address to store each element data in memory regions positioned sufficiently apart one another in address space.

TECHNICAL FIELD

The present invention relates to interleaving devices for interleaving adata block having a plurality of items of element data arranged on atime-series basis to shuffle time-series order of the element data andoutputting its result, and to deinterleaving devices for deinterleavinga plurality of items of element data which have been interleaved andshuffled in time-series order and outputting its result.

BACKGROUND ART

A method of storage with interleaving has heretofore been known forstoring confidential data.

In the method of data storage with interleave, a series of data blocksis divided into a plurality of items of element data, time-series orderof the element data is shuffled, and the element data shuffled intime-series order is stored in a memory. This ensures confidentiality ofthe original data block.

Known for storing the data with interleave processing is a method ofshuffling the time-series order of the plurality of items of elementdata according to a predetermined rule and storing each element data ina memory in the shuffled order, a method of calculating an address towhich the element data is to be stored with use of an arithmeticoperation, and a method of storing each element data to the addresscalculated.

A method is proposed wherein each element is stored to a correspondingaddress by using a table on which a random number is written as anaddress for every element data [JP-A No. 347076(1993)].

However, any method of the three methods stated above adopts a singledata conversion rule for interleave processing, i.e., a single shufflingrule, a single arithmetic expression, or a single table. Accordingly, ifthe single data conversion rule is known to anyone else, the data blockcan be easily restored to its original by anyone else, entailing theproblem of impaired reliability as to confidentiality of the data block.

An object of the present invention is to provide an interleaving deviceand a deinterleaving device for ensuring the high reliability as toconfidentiality of the data block.

DISCLOSURE OF THE INVENTION

The present invention provides an interleaving device for interleaving adata block having a plurality of items of element data arranged on atime-series basis to shuffle time-series order of the element data andoutputting its result, the interleaving device comprising:

-   -   memory means for storing a plurality of items of element data        being interleaved,    -   rule storing means for, in order to convert order data        representing time-series order of each element data constituting        the data block to address data representing an address in the        memory means, storing a plurality of data conversion rules for        processing each order data for a plurality of steps of data        conversion,    -   data conversion means for processing each order data for a        plurality of steps of data conversion according to the data        conversion rules, and    -   data storing means for storing each element data to a        corresponding address in the memory means based on the address        data as to each order data obtained by the steps of data        conversion processing.

A plurality of data conversion rules storage portions provided with therule storing means comprise memory regions of physically differentmemory chips, or comprise a plurality of memory regions positioned apartone another in address space of the same memory chip.

With the interleaving device of the present invention, the order dataarranged in a regular order is processed for the plurality of steps ofdata conversion, to obtain address data representing irregular addressarrangement. Each element data constituting the data block is stored tosuch irregular address, so that even if element data is read out fromthe memory means and arranged in an order of address, the data block isnot restored to its original, whereby the data content cannot bedecoded.

The plurality of data conversion rules, as described above, arenecessary to read out from the memory means the plurality of items ofelement data stored and to restore the data block to its original. Theplurality of data conversion rules are stored in the memory regions ofphysically different memory chips, or in a plurality of memory regionspositioned apart one another in address space of the same memory chip,so that it is difficult for someone else to know all the data conversionrules. Even though one data conversion rule is known to anyone else, thedata block cannot be restored to its original by the one data conversionrule. Thus the data storage method of the invention ensures higherreliability as to the confidentiality of the data block than theconventional method.

Stated specifically, the rule storing means stores a random number tablefor storing a random number sequence, and a function expression whereininput data is a variable. The data conversion means comprises firstconversion means for reading out a random number of order correspondingto order data from the random number table and second conversion meansfor performing the operation based on the function expression with inputdata of the random number read out from the random number table andcalculating address data.

According to the specific construction, the order data arranged in theregular order is each processed for data conversion using the randomnumber table, to obtain data having excellent randomness. Each data isprocessed for calculation based on the function expression, having eachdata converted further, to obtain address data which cannot be guessedfrom the original order data.

The present invention provides a deinterleaving device fordeinterleaving a plurality of items of element data which have beenshuffled in time-series order resulted from interleave processing of adata block having the element data arranged on a time-series basis andoutputting its result, the deinterleaving device comprising:

-   -   memory means for storing a plurality of items of element data        being interleaved,    -   rule storing means for, in order to convert order data        representing time-series order of each element data constituting        the data block to address data representing an address in the        memory means, storing a plurality of data conversion rules for        processing each order data for a plurality of steps of data        conversion,    -   data conversion means for processing each order data for a        plurality of steps of data conversion according to the data        conversion rules, and    -   data reading means for reading out element data from a        corresponding address in the memory means based on address data        as to each order data obtained by the steps of data conversion        processing, and restoring the data block to its original. A        plurality of data conversion rules storage portions provided        with the rule storing means comprise memory regions of        physically different memory chips, or comprise a plurality of        memory regions positioned apart one another in address space of        the same memory chip.

With the deinterleaving device of the invention, each element dataconstituting the data block is interleaved by the interleaving devicedescribed, and is stored in a predetermined address of the memory means,i.e. an address which is represented by the address data obtained by thesteps of data conversion processing to the order data as to each elementdata.

Thus the steps of data conversion processing are conducted to the orderdata as to each element data, to obtain address data representing anaddress to which each element data is stored. Element data is read outfrom an address represented by the address data thus obtained, arrangingthe element data read out, thereby restoring to its original the datablock having a plurality of element data arranged in time-series order.

As described above, a plurality of data conversion rules are necessaryto restore the data block to its original. The plurality of dataconversion rules are stored in the memory regions of physicallydifferent memory chips, or a plurality of memory regions positionedapart one another in address space of the same memory chip, so that itis difficult for someone else to know all the data conversion rules.Even though one data conversion rule is known to anyone else, the datablock cannot be restored to its original with the one data conversionrule. Thus the data storage method of the invention ensures higherreliability as to the confidentiality of the data block than theconventional method described above.

Stated specifically, the rule storing means stores a random number tablefor storing a random number sequence, and a function expression whereininput data is a variable. The data conversion means comprises firstconversion means for reading out a random number of order correspondingto order data from the random number table and second conversion meansfor performing the calculation based on the function expression withinput data of a random number read out from the random number table andcalculating address data.

Thus the plurality of element data being interleaved with use of therandom number table and the function expression of the interleavingdevice can be restored to the data block having the originaltime-series.

As described above, the present invention provides an interleavingdevice and deinterleaving device which ensures high reliability as tothe confidentiality of the data block.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the construction of a signal recordreproduction device embodying the invention;

FIG. 2 is a diagram showing the construction of music data andauthentication data to be transferred from a personal computer to thesignal record reproduction device;

FIG. 3 is a diagram showing a signal recording format of a flash memoryincorporated in a microcomputer;

FIG. 4 is a diagram for illustrating a method for interleaving a mainencryption key;

FIG. 5 is a diagram for illustrating a method for deinterleaving themain encryption key;

FIG. 6 is a flow chart showing a data transferring procedure to beperformed by the personal computer;

FIG. 7 is a flow chart showing a music data reproducing procedure to beperformed by the microcomputer of the signal record reproduction device.

BEST MODE OF CARRYING OUT THE INVENTION

With reference to the drawings, an embodiment of the present inventionwill be described in detail.

In recent years music data compressed in MP 3 (MPEG AUDIO LAYER-3)format or AAC (ADVANCED AUDIO CODING) format is available on theInternet.

A portable signal record reproduction device 1 shown in FIG. 1 can beconnected to a personal computer 2, and music data is downloaded fromthe Internet to the computer 2. The device 1 can receive the music datadownloaded from the Internet to the computer 2 with the device connectedto the computer 2, and can record the received music data in a memorycard 11.

The computer 2 only downloads sound data authenticated for reproductionby a distributor. Added to music data downloaded is authentication datafor indicating that the music data is authenticated for reproductionwith the signal record reproduction device 1. After the authenticationdata is processed for encryption such that only the signal recordreproduction device 1 can decrypt the data encrypted, the music data andthe authentication data encrypted are transferred to the signal recordreproduction device 1.

With the signal record reproduction device 1, the music data and theauthentication data transferred from the computer 2 are recorded in thememory card 11.

When the user selects one music data to reproduce it, one mainencryption key is decrypted to decrypt a plurality of sub encryptionkeys with use of the main encryption key. The authentication data addedto the music data selected by the user is thereafter decrypted with useof the sub encryption keys, judging whether the music data isauthenticated for reproduction with the device based on the result ofdecoding of the authentication data. Only if the music data isauthenticated for reproduction with the device, the music data isreproduced to deliver outside the reproduced sound through a headset(not shown).

Even if the other signal record reproduction device is connected to thecomputer 2 receiving music data and authentication data from thecomputer 2 to record the data stated in the memory card, an incorporatedmemory does not have stored therein the sub encryption keys fordecrypting the authentication data and the one main encryption key fordecrypting the sub encryption keys, so that the authentication datacannot be decoded and the music data cannot be reproduced.

Accordingly the music data can be reproduced only by the signal recordreproduction device 1 of a person who is authenticated for reproductionof the music data, whereby copyright of the distributor of the musicdata is protected.

The other signal record reproduction device described can reproduce themusic data if the other device obtains the main encryption key and thesub encryption keys of the signal record reproduction device 1 todecrypt the sub encryption keys with use of the main encryption key,thereafter restoring the authentication data with use of the subencryption keys, further obtaining an identification number of thesignal record reproduction device 1 which will be stated below.

Accordingly ensuring the confidentiality of the main encryption key isnecessary for the secure protection of copyright of the music datadistributor.

In this embodiment, the present invention is embodied into interleaveprocessing and deinterleave processing for the main encryption key, tosecurely protect copyright of the music data distributor.

First the construction and the operation of the personal computer 2 andthe signal record reproduction device 1 will be specifically described,respectively, and then interleave processing and deinterleave processingfor the main encryption key will be specifically described.

The personal computer 2 is provided with data management software havinga function of downloading only music data authenticated for reproductionby a distributor, a function of communicating with a signal recordreproduction device of a person who is authenticated for reproduction ofmusic data, and a function of adding authentication data to the musicdata downloaded and encrypting the authentication data.

FIG. 6 shows a data transferring procedure to be performed by thepersonal computer 2. A memory (not shown) incorporated in the computer 2has stored therein an identification number of the signal recordreproduction device 1 (Device ID).

A signal record reproduction device is connected to the computer 2, asillustrated, first in step S1 an inquiry is made as to whether thesignal record reproduction device that has been connected is valid basedon the identification number stored in the memory incorporated, i.e., asto whether the signal record reproduction device that has been connectedis the signal record reproduction device 1. If the answer is thenegative, the same inquiry is repeated in step S1. On the other hand,when the answer is the affirmative, step S2 follows.

In step S2 an inquiry is made as to whether a transferring key providedwith the signal record reproduction device 1 is manipulated. When theinquiry is answered in the negative, step S1 follows again.

If the user depresses the transferring key to transfer desired musicdata to the signal record reproduction device, the answer for step S2 isanswered in the affirmative, followed by step S3 wherein an encryptionkey is generated for encrypting authentication data based on theidentification number stored in the memory incorporated, as will bedescribed below. Thereafter in step S4 the authentication data is addedto the music data selected by the user as shown in FIG. 2.

Subsequently in step S5 the authentication data is encrypted with use ofthe encryption key prepared in step S3. In step S6 the music data andthe authentication data encrypted are transferred to the signal recordreproduction device 1 to complete the procedure.

With the procedure described, the sound data downloaded on the Internetand the authentication data encrypted are transferred to the signalrecord reproduction device 1.

On the other hand, the signal record reproduction device 1 is providedwith a memory card/PC communications controller 10 for communicatingwith the computer 2 and writing and reading data for the memory card 11,as shown in FIG. 1. The controller 10 receives the music data and theauthentication data transferred from the computer 2, as described above,writing the music data and the authentication data in the memory card11.

The controller 10 is connected to the microcomputer 12. Connected to themicrocomputer 12 are a nonvolatile rewritable memory 17, e.g. EEPROM,manipulation keys 18 and a LCD 19. Stored in the memory 17 are, asdescribed above, a plurality of sub encryption keys for decrypting theauthentication data that has been encrypted and a main encryption keyfor encrypting the sub encryption keys and decrypting the sub encryptionkeys that have been encrypted.

When the user selects one music data to depress a reproduction key, themicrocomputer 12 decrypts the main encryption key with a methoddescribed below, decrypting the sub encryption keys with use of the mainencryption key that has been decrypted. Thereafter, the authenticationdata added to the music data is decrypted with use of the sub encryptionkeys to decode the authentication data, as described above. Based on thedecode result an inquiry is made as to whether the music data selectedby the user is authenticated for reproduction.

If the music data selected by the user is authenticated forreproduction, the microcomputer 12 gives the memory card/PCcommunications controller 10 a reading command for the music data.

The memory card/PC communications controller 10 is given the readingcommand by the microcomputer 12 to read out the music data from thememory card 11 to feed the music data to the microcomputer 12.

The music data fed to the microcomputer 12 is first fed to a decodecircuit 13 and is given predetermined signal processing such asdecompression processing. Thereafter the music data is fed to ananalogue conversion circuit 14 to be converted to analogue audiosignals. The analogue audio signals are fed to an amplifier circuit 15to be amplified, and thereafter the signals are fed to a headset (notshown) via a headset terminal 16 and delivered outside as sound throughthe headset.

In this way only the music data that has been authenticated forreproduction is reproduced.

With reference to FIGS. 4 and 5, interleave processing and deinterleaveprocessing for the main encryption key which is a characteristic of thesignal record reproduction device 1 embodying the invention will bedescribed below.

In the interleave processing, a data block representing the mainencryption key is divided into a plurality of items of element data (Ato T) each having data amount of 1 byte, as shown in FIG. 4( a). Addressdata representing an address to which each element data is to be storedis derived with use of a table and a function expression. The flashmemory (not shown) incorporated in the microcomputer 12 stores the tableand the function expression in two memory regions 121, 122 positionedsufficiently apart one another in address space as shown in FIG. 3.

Stored in the table are random numbers having the same number as that ofthe element data constituting the data block of the main encryption key,as shown in FIGS. 4( b) and 5(a). The random numbers are generated by arandom number generator, and are transferred from the random numbergenerator to the microcomputer 12, and are written to the flash memory.

On the other hand, address data is calculated from the functionexpression wherein a random number stored in the table is a variable X.(for example, Y=aX+b, a, b: constant value)

In interleave processing, with respect to each element data constitutingthe data block of the main encryption key, a random number stored in thesame order as that of each element data is read out from the table shownin FIG. 4( b). Thereafter, an operation is performed with the functionexpression wherein a random number read out is a variable to calculateaddress data, as shown in FIG. 4( c). Each element data is stored to anaddress represented by the address data calculated, as shown in FIG. 4(d)

For example, with respect to the third element data C, the third randomnumber “7” is read out from the table shown in FIG. 4( b), and then anoperation is performed with the function expression wherein a randomnumber is a variable to calculate address data, storing the element dataC to an address represented by the address data calculated.

In interleave processing described, with respect to a plurality of itemsof element data (A to T) constituting the data block of the mainencryption key, the random numbers having excellent randomness areobtained from the table shown in FIG. 4( b). The random numbers are eachprocessed for the operation with the function expression, to calculateaddress data to be given further data conversion, storing the elementdata (A to T) to addresses represented by the address data,respectively.

In this way, time-series order of the element data constituting the datablock of the main encryption key is random shuffled, as shown in FIG. 4(d), and are stored in the memory 17.

In deinterleave processing, the first random number “12” is read outfrom a table shown in FIG. 5( a), and an operation is performed with thefunction expression wherein a random number read out is a variable, asshown in FIG. 5( b) to calculate address data. Element data A is readout, which is stored to an address represented by the address datacalculated as shown in FIG. 5( c). Subsequently the second random number“2” is read out from the table shown in FIG. 5( a), and an operation isperformed with the function expression wherein a random number read outis a variable, as shown in FIG. 5( b) to calculate address data. Elementdata B is read out, which is stored to an address represented by theaddress data calculated as shown in FIG. 5( c).

In the same manner as the above, the operation is repeated as follows:the random numbers are sequentially read out from the table shown inFIG. 5( a) according to a storing order, to obtain address data byprocessing the random number read out for the operation with thefunction expression, reading out element data based on an addressrepresented by the address data obtained. The element data thus obtainedare arranged according to an order of read-out from the table. In theinterleave processing described above, a random number that is stored inthe same order as that of each element data is read out from the tableshown in FIG. 4( b), so that element data are arranged according to anorder of read-out from the table of FIG. 5( a), thereby obtaining anoriginal data block wherein the element data (A to T) are arranged intime-series order as shown in FIG. 5( d).

FIG. 7 shows the music data reproducing procedure to be performed by themicrocomputer 12 of the signal record reproduction device 1.

As illustrated, first in step S11 an inquiry is made as to whether areproduction key is manipulated. If the answer is the negative, the sameinquiry is repeated in step S11.

On the other hand, when the user selects one music data from among aplurality of items of music data recorded in the memory card 11 todepress the reproduction key, the answer for step S11 is answered in theaffirmative, followed by step S12 wherein the main encryption key isdecrypted according to the method described.

Subsequently in step S13 a plurality of sub encryption keys aredecrypted with use of the main encryption key, followed by step S14wherein with use of the sub encryption keys, authenticated data added tothe music data is decrypted and decoded.

In step S15 an inquiry is made as to whether based on the decoded resultstated above, the music data selected by the user is authenticated forreproduction with the device 1. When the answer is the negative, thesequence returns to step S11. On the other hand, when the answer is theaffirmative, step S16 follows to give a reading command to a memorycard/PC communications controller 10, and then the sequence returns tostep S11. The memory card/PC communications controller 10 with thecommand given reads out the music data selected by the user from thememory card 11. As a result the music data selected by the user isdelivered outside as sound through the headset.

With the procedure described, only the music data that the distributorauthenticates for reproduction with the device 1 is reproduced.

With the signal record reproduction device 1, the table and the functionexpression used in the interleave processing and deinterleave processingof the main encryption key are each stored in the two memory regions121, 122 positioned sufficiently apart one another in address space of aflash memory incorporated in a microcomputer, so that it is difficultfor someone else to know both the table and the function expression.Even if a single data conversion rule of one of the table and thefunction expression is known to anyone else, the data block of the mainencryption key cannot be restored with the single data conversion rule.Thus the data storing method ensures the higher reliability as toconfidentiality of the data block than the conventional method.

The data block of the main encryption key is interleaved with use of onetable and one function expression according to the example described,whereas the method is not limitative; the block can be interleaved withuse of two tables or with use of two function expressions.Alternatively, the number of the data conversion rules is not limited totwo; three or more data conversions rules is also usable.

Furthermore, the table and the function expression are stored in twomemory regions 121, 122 positioned apart one another in address space ofthe same flash memory according to the example described, whereas theconstruction is not limitative; the table and the function expressioncan be each stored in memory regions of physically different two memorychips.

1. An interleaving device for interleaving a data block having aplurality of items of element data arranged on a time-series basis toshuffle time-series order of the element data and outputting its result,the interleaving device comprising: memory means for storing a pluralityof items of element data being interleaved, rule storing means forstoring a random number table for storing a random number sequence and afunction expression wherein input data is a variable, first conversionmeans for reading out from the random number table a random number oforder corresponding to order data representing time-series order of eachelement data constituting the data block, second conversion means forperforming an operation based on the function expression with input dataof the random number being read out from the random number table andcalculating address data representing an address in the memory means,and data storing means for storing each element data to a correspondingaddress in the memory means based on the address data as to each orderdata being calculated by the second conversion means, the interleavingdevice being characterized in that the rule storing means comprisesmemory regions of two physically different memory chips or comprises tworule storing portions comprising two memory regions positioned aparteach other in address space of the same memory chip, and one of the rulestoring portions stores the random number table, and the other of therule storing portions stores the function expression.
 2. Adeinterleaving device for deinterleaving a plurality of items of elementdata which have been shuffled in time-series order resulted frominterleave processing of a data block having the element data arrangedon a time-series basis and outputting its result, the deinterleavingdevice comprising: memory means for storing a plurality of items ofelement data being interleaved, rule storing means for storing a randomnumber table for storing a random number sequence and a functionexpression wherein input data is a variable, first conversion means forreading out from the random number table a random number of ordercorresponding to order data representing time-series order of eachelement data constituting the data block, second conversion means forperforming an operation based on the function expression with input dataof the random number being read out from the random number table andcalculating address data representing an address in the memory means,and data reading means for reading out element data from a correspondingaddress in the memory means based on the address data as to each orderdata being calculated by the second conversion means and restoring thedata block to its original, the deinterleaving device beingcharacterized in that the rule storing means comprises memory regions oftwo physically different memory chips or comprises two rule storingportions comprising two memory regions positioned apart each other inaddress space of the same memory chip, and one of the rule storingportions stores the random number table, and the other of the rulestoring portions stores the function expression.